Unitary, circumferentially edge wound friction material clutch plate, and method of making same

ABSTRACT

A friction material has a plurality of connected sections defined by a plurality of notches therebetween. Each notch has an apex which compensates for tear and compression of the friction material when the friction material is circumferentially placed on a flat surface of an annular core plate. In certain embodiments, a multiple linked loading device places the notched friction material adjacent a core plate to form a clutch plate.

TECHNICAL FIELD

The present invention relates generally to a method and apparatus formaking a friction plate having a friction material facing and to thefriction material itself. More specifically, the invention is directedto a method and apparatus for making a friction plate having a unitary,or single, circumferentially edge wound friction material on one or bothsides of a core plate.

The present invention also relates generally to automatic transmissionclutch plates, and more particularly, to a clutch plate having afriction material bonded thereto where the friction material is blankedas a straight notched strip of friction material. The friction materialis formed into a circular shape and is bonded to the core plate.

BACKGROUND OF THE PRESENT INVENTION

The present invention relates to a method and apparatus for makingfriction materials for use with a wet-type multi-plate clutch andfurther relates to the friction material itself. The prior artmulti-plate clutches generally comprise a plurality of interleavedclutch discs and reaction plates which engage to provide thetransmission of energy from a drive engine to a drive wheel. Wet-typeclutches also utilize a lubricant such as oil to reduce clutch wear,cool the friction facings of the clutch discs and provide desiredhydrostatic forces between the clutch plates and clutch discs.

The friction material is usually composed of fibrous paper whichnormally is impregnated with a phenolic resin. The friction material iscommonly cut from a continuous strip of rectangular sheeting composed ofthe friction material which is fed through the die or cutting apparatus.The friction material is relatively expensive and, therefore, it isdesirable to optimize the elimination of waste from the manufacturingprocess.

Once the friction material is impregnated with the phenolic thermosetresin, it cannot be economically recycled. Further, elimination of wasteproduct from the manufacture process assists in meeting compliancestandards. The proper disposal of any scrap is the focus of increasingregulation by current environmental regulators. Any scrap resulting fromthe cutting process must be disposed of in an appropriate manner and,because of the materials from which the friction facing is manufactured,this disposal is becoming increasingly costly.

Further, in the interest of optimizing clutch life, operationalsmoothness, and cooling efficiency for the friction facings, theliterature and art relating to wet-type clutches provides numerousclutch designs producing a large variety of friction facing materialsand designs of friction facing materials. A common friction facing,currently available is shown by the disclosure of U.S. Pat. Nos.4,260,047 and 4,674,616 which disclose friction discs, for use withclutches, which are formed from friction material and produced from thejoining of a plurality of separate arcuate segments. The arcuatesegments are pre-grooved to allow cooling oil to flow over the frictionfacing during clutch operation.

The U.S. Pat. Nos. 5,094,331, 5,460,255, 5,571,372, 5,776,288, 5,897,737and 6,019,205 disclose clutch friction plates having a large number ofindividually placed friction material segments on the plate. Thesegments are in a spaced apart relationship such that an oil groove isprovided between every adjacent segment.

The U.S. Pat. Nos. 3,871,934 and 4,002,225 show a friction materialwound around the outer periphery disc, such that it overlaps the disc onboth sides. The overlap is then cut at intervals around the peripheryand folded onto the surface of the disc.

The U.S. Pat. No. 5,335,765, discloses a friction member having sets offirst grooves and second grooves disposed in a radial plane and inclinedobliquely backwardly in relation to the direction of rotation.

The U.S. Pat. Nos. 5,615,758 and 5,998,311 show friction yarn facingmaterials with no grooves, but rather, the warp and fill yarns formchannels to allow for the flow of fluid therethrough.

The manufacturing of many of these friction materials produce a largeamount of unused or scrap material. It is, therefore, a primary objectof the invention to effectively reduce the amount of scrap remainingafter cutting of the friction material.

It is also desired that the sufficient cooling and lubrication of thefriction material and clutch plates occurs such that smooth engagementand disengagement of the clutch is maintained without creating excessivewear on the members of the clutch and friction facing material. Manyprior art friction material designs incorporate the use of grooves orslot patterns within the facing material to achieve the desired coolingand lubrication by allowing the passage of a fluid such as oil throughthe friction facings. Such cooling grooves are generally produced fromone of three labor intensive methods. One method provides that thefriction material is pre-grooved prior to being cut and applied to theclutch plate in a manner such as that taught by U.S. Pat. No. 4,260,047.Another method of producing grooves utilizes configured tooling tocompress portions of the friction material during the hot pressurebonding process. The third method involves producing cut grooves in afinished friction plate by mounting the plate onto a fixture and passingmultiple milling and grinding wheels through the friction material tocut distinct grooves of desired depth and definition.

The common failing of the previous designs of friction materials lies inthe formation of intricate shapes and designs which consequently leadsto manufacturing complexities, increased tooling costs, increased scrapproduction and the resultant concerns regarding proper disposal of thescrap. Further, the previous friction materials are all individuallymanufactured to specific types of friction clutches and, generallyspeaking, cannot be used in a wide variety of applications.

It is an object of the present invention to manufacture a frictionclutch plate having distinct cooling groove patterns of desired depthand definition without the need for secondary operations and attendantmachinery.

It is another object of the invention to provide an apparatus for makinga continuous friction material which nearly scrapless in itsmanufacture.

It is yet another object of the present invention to provide a methodand apparatus for making a friction material having a plurality ofdesired grooves therein.

Yet another object of the invention is to provide a method and apparatusfor making a friction material having design advantages designated toproduce enhanced product performance, and specifically reduced drag andimproved shift feel (i.e., the ratio of end point coefficient offriction/midpoint coefficient of friction).

Yet a further object of the invention is to produce a method andapparatus for making a friction material having the capability ofmaintaining static pressure and holding dynamic fluid flow within thegrooves of the friction material during operation of the engaged clutchdisc and clutch plate.

It is another object of the invention to provide a friction materialwhich is universally applicable to differing types of clutch usage.

Yet another object of the invention is to provide a method for bondingthe friction material to a core plate by induction bonding, or othersuitable methods, of the friction material to the core plate.

Disclosure of the Present Invention

A unitary, circumferentially edge wound friction material and a methodand apparatus for making a wet-type friction clutch plate are disclosed.The friction material has a plurality of A-notches and is a unitary, orcontinuous strip of material. The friction material is oriented on theclutch plate so as to create desired lubrication and cooling pumpingfunctions through full depth oil channels created in the frictionmaterial. The orientation of the notches in the friction materialachieves a desired direction of oil flow radially into or out of theclutch plate and also creates a desired amount of hydrostatic pressure.The size of the friction material and the shape, spacing and orientationof the notches all operate to control the degree of fluid pumping, thehydrostatic pressure, and the amount of cooling of the friction clutchplate.

In particular, the present invention describes a method and apparatusfor making a clutch plate with an unitary, circumferentially edge woundfriction material. The friction material is blanked with a desirednumber of notches as a straight strip of material and then is woundcircumferentially to cover a face of the core plate. The notches allowthe strip to be edge wound around an outer circumference of the coreplate and also to produce desired grooves in the completed clutch plate.

In a preferred aspect, the notches have a generally Λ-shape where eachnotch has an apex which compensates for tear and compression of thefriction material when the friction material is circumferentially placedon the core plate. In a preferred aspect, the apex has a generallycircular shape which prevents the friction material from fracturing orseparating. The unique geometry of the Λ-notch and its apex promotesboth desirable tension and desirable compression in the frictionmaterial.

The notched friction material provides a significant improvement(greater than 50%) (i.e., from 18-32% with full ring to 80-90% withnotch friction material depending on geometry) in friction materialutilization over conventional full ring blanked friction facings. Incertain embodiments, the notches are “dead end” such that there is nogroove exit at the outside diameter of the friction plate. These “deadend” grooves retain the fluid at the friction interface. This isespecially desirable in low fluid flow application, (where it isdifficult to obtain high fluid flow).

In another embodiment, the a portion of the apex of the notches isremoved, preferably by being sanded, or chamfered, such that there isrestricted fluid flow from one end of the groove to the other end of thegroove. These restricted flow groove exits provide a reduction inparasitic drag when the clutch is not applied.

One criterion in determining the shape, spacing and orientation of thenotches in the friction material of this invention is the ratio of thecircumference (360°) to the desired number of grooves in the length offriction material to be placed on the core plate. That is, 360°÷numberof grooves=angle of each Λ-notch.

As the performance requirements for automobiles become more stringent,the clutches must be able to provide high torque at high RPMs therebyoperating efficiently at high temperatures. This performance requirementtherefore demands more expensive, higher performance materials for useas the friction material. Thus, as the material costs increase, thepresent invention provides for an efficient method to produce a frictionplate which minimizes the friction surface area while simultaneouslystriving to maintain cooling and lubrication requirements. The Λ-notchedfriction material is responsive to the greater heat generation and theheat dissipation within the clutch which are necessary to meet theperformance standards for the higher RPM/smaller engines common totoday's automobile.

Another important performance requirement of today's automotive clutchesis to produce minimal drag when the clutch is not applied, e.g. an openreverse clutch that is rotating but not applied when cruising at highwayspeed. Lower open clutch pack drag translates into higher fuelefficiency of the vehicle. The present invention produces lower openpack (parasitic) drag than other conventional designs (non-groove, cutgrooved, molded groove).

In the method of making the clutch plate of the present invention, astrip of friction material is blanked out, or notched, with the desiredΛ-notch geometry defining each notch. The blanked out strip of frictionmaterial is cut to a desired length. The length of Λ-notched frictionmaterial is picked up by a loading device, and is circumferentiallyplaced adjacent a bonding nest. The bonding nest is used to helpassemble the components of the clutch plate: the Λ-notched frictionmaterial and a core plate. The loading device comprises a plurality ofconnected links where each link has at least one vacuum port. The linkedloading device is moved adjacent the cut strip of friction material. Thevacuum is engaged which allows the loading device to pick up the cutstrip of friction material. The links of the linked loading device aremoved, or laterally rotated, to form a closed circle. The linked loadingdevice is positioned in coaxially alignment with the nest. The vacuum isreleased and the friction material is placed in the nest.

A core plate is placed in the nest and the above described process isrepeated to place a second strip of friction material on top of the coreplate.

Thereafter, the friction material is adhered to the core plate in adesired manner. The method for adhering the core plate involves using athermosetting adhesive coating on the core plate. Thereafter, thefriction material and core plate are compressed and heated in a suitablemanner. The core plates can be stacked into a multiple nestingarrangement and heated in an oven. In another method, the assembled coreplate with the friction materials adjacent thereto can be heated byconduction. Yet another method involves heating the core plate andfriction materials adjacent thereto for with an induction coil.

The various embodiments of the present invention will be more readilyunderstood, in their application to the objectives of this invention byreference to the accompanying drawings and the following description ofthe preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic flow diagram showing an assembly process formaking a clutch plate with a unitary, circumferentially edge woundfriction material.

FIG. 2 is a schematic top plan view of a stamping die for producing aΛ-notched friction material strip.

FIG. 3 is a schematic side elevational view of the stamping die of FIG.2.

FIG. 4 is a plan view of a multiple link loading device, partially inphantom.

FIG. 5 is a schematic side elevational view, partially in phantom, ofthe multiple link loading device shown in FIG. 4.

FIG. 6 is a schematic side elevational, cross-sectional view of aportion of a link in the linked loading device.

FIG. 7 is a schematic plan view of a step in forming a unitary strip offriction material.

FIG. 8 is similar to FIG. 7 and shows another step in forming a unitarystrip of Λ-notched friction material.

FIG. 9 is similar to FIG. 7 and shows another step in loading a unitarystrip of friction material.

FIG. 10 is similar to FIG. 7 and shows another step in loading a unitarystrip of friction material.

FIG. 11 is a schematic plan view showing a strip of friction materialplaced adjacent a core plate, in the bonding nest.

FIG. 12 is a schematic, cross-sectional, side elevational view ofopposing strips of friction material adjacent an adhesive-coated coreplate in an assembly/bonding nest.

FIG. 13 is a schematic side elevational view, partially in cross sectionand partially in phantom, showing a plurality of assembly/bonding nestsclamped together for placement in a heating oven.

FIG. 14 is an enlarged view of the area shown in FIG. 13.

FIG. 15 is a schematic side elevational view, partially in cross sectionand partially in phantom, showing an induction bonding apparatus forheating an assembly/bonding nest.

FIG. 16 is a schematic side elevational view, partially incross-section, showing heating of an assembly/bonding nest using aconduction device.

FIG. 17 is a top plan view of a strip of a Λ-notched friction materialdisposed in a circular shape.

FIG. 18 is a schematic view of a Λ-notch in the friction material ofFIG. 17, prior to being circumferentially wound.

FIG. 19 is a schematic view of an apex of a Λ-notch in the frictionmaterial of FIG. 17, as circumferentially wound.

FIG. 20 is a partial plan view of a part of an alternative embodiment ofthe Λ-notched friction material of the present invention.

FIG. 21 is a partial plan view of a part of an alternative embodiment ofthe Λ-notched friction material of the present invention.

FIG. 22 is a partial plan view, partially in phantom, of a Λ-notchedfriction material on a core plate.

FIG. 23 is a partial plan view, partially in phantom, of a frictionmaterial on a core plate, and showing chamfering of an outer edge orcircumference of the friction material.

FIG. 24 is a view taken along the line 24—24 in FIG. 23.

FIG. 25 is a view taken along the line 25—25 in FIG. 23.

FIGS. 26A-D are graphs showing the SAE MuPVT test (981D) for Λ-notchedfriction material with full depth, dead end grooves (i.e., no exits).

FIGS. 27A-D are graphs showing the SAE MuPVT test (981D) for a Λ-notchedfriction material with chamfer sanded edges.

FIGS. 28A-D are graphs showing the SAE MuPVT test (981D) for a Λ-notchedfriction material with full depth, dead-end grooves (i.e., no exits).

FIGS. 29A-D are graphs showing the SAE MuPVT test (981D) for a Λ-notchedfriction material with chamfer sanded edges.

FIGS. 30A-D are graphs showing the SAE MuPVT test (981D) for a Λ-notchedfriction material with full depth, dead-end grooves (i.e., no exits).

FIGS. 31A-D are graphs showing the SAE MuPVT test (981D) for a Λ-notchedfriction material with chamfer sanded edges.

FIG. 32 is a graph showing the results of drag tests for Λ-notchedfriction materials, as compared to conventional non-grooved, 25 cutparallel and 56 molded radial friction materials.

FIG. 33 is a graph showing the results of the SAE (1015A) T-N durabilitytests for Λ-notched friction materials *with exits and • without exits.

FIG. 34 is a graph showing the results of the SAE (1014) hot spot testsfor Λ-notched friction materials with exits and without exits ascompared to conventional 25 cut parallel friction materials.

FIG. 35 is a schematic plan view, partially in phantom, of an indexingapparatus for dispensing a Λ-notched friction material.

FIG. 36 is a schematic plan view of an alternative indexing apparatusfor dispensing a Λ-notched friction material.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 shows a flow diagram for producing a clutch plate with a unitary,circumferentially edge wound friction material. Referring first to theright hand side of the figure, the steel is received, straightened, andblanked as a core. The core is then cleaned, acid-etched and theadhesive is applied; in various embodiments, when the adhesive is athermosetting adhesive, a B stage thermosetting process is used to“preset” the adhesive material. Referring now to the left hand side ofthe figure, the raw materials are received and the friction material ismanufactured. The friction material is slit into narrow coils having adesired width. The material is blanked and Λ-notches are cut into thefriction material using the apparatus of the present invention. Thecenter of the flow diagram shows the process during a continuousoperation where a loaded bonding nest is removed and a new empty nestloaded into the machine. A linked loading device forms and inserts afirst strip of the notched friction material into the bonding nest. Aglued core plate is loaded into the bonding nest and a second strip ofthe notched friction material is placed on top of the glued core. Theloaded bonding nest is removed and the cycle is repeated for a desirednumber of times. Thereafter, all nests are assembled, clamped, andheated to bond the friction material to the core.

In certain embodiments, a portion of the friction material adjacent theedges of each clutch plate with the unitary edge wound friction materialon opposing sides thereof is removed, for example, by being chamfersanded. The chamfer sanding of the edges provides the desired clutchplate with restricted, or partially opened, grooves. Finally, the clutchplates are inspected and packed for delivery.

Referring to FIG. 2, a stamping die 8 for simultaneously producing twostrips of friction material 10 and 10′ is shown. It is to be understoodthat, while not shown, the die 8 can be configured so that only onestrip of friction material 10 is cut. The stamping die 8 generallyincludes a die set 11 operatively connected to a die block 12. Astripper 13 is positioned in a spaced apart relationship to the dieblock 12. A punch holder 14 is positioned adjacent an upper portion ofthe die set 11. A notching punch 15 is operatively connected to the dieset 11. A cut off or sliding parting punch 16 is positioned downstreamof the punch 15 to provide a cut off of predetermined lengths of thefriction material.

The cut off punch 16 is operatively mounted to a cut off block 17 whichis retracted by a spring 19 held in place by a spring block 20. Aperforated punch 22 is operatively positioned within the punch holder14.

The stamping die 8 further includes a stock guide 23 operativelypositioned on a stock support 25. The friction material 10 is guidedalong on the stock guide 23 as it enters the stamping die 8. Thefriction material 10 is supported on a strip support plate 27 afterbeing punched and cut.

As will be explained in detail below, the punch 15 provides a desirednumber of unique Λ-notches 220 in the friction material 10. The cut offor parting punch 16 is activated after any number of desired strokes ofthe notching punch 15 to cut the strip of friction material off to adesired length.

The unique Λ-notched geometry determines the resulting oil groove widthand how well the strip of friction material conforms to a bonding nest,as will be described in detail below. The pitch, or number, of Λ-notchesin a strip of material also has an influence on how well the formedfriction material conforms to the bonding nest as will also be describedin detail below. In certain preferred embodiments, the manufacturingprocess is most efficient when the strip of friction material containsfrom about 12 to about 40 and preferably about 16 to about 25 Λ-notchesin a desired length of friction material.

The blanked out strip of friction material 10 then moved to an assemblylocation. It is to be understood that the present invention contemplatesautomatically moving the length of friction material 10 from the stripsupport plate 27 to a point adjacent a multiple linked loading device40, as shown in FIGS. 4-11.

FIG. 4 generally shows a multiple link loading device 40 having aplurality of links 42. It is to be understood that the number of linksin the device 40 is preferably the same as the number of notchedsections of the strip of friction material 10. Each link 42 has at leastone vacuum port 44, as can be seen in FIGS. 5 and 6. The linked loadingdevice 40 is moved adjacent and into contact with a length of notchedfriction material 10, as shown in FIG. 5.

FIG. 5 generally shows a schematic illustration of the linked loadingdevice 40 in a pick up or straight position and firmly holding thelength of notched friction material.

FIG. 6 generally shows a schematic enlarged view of a link 42 and thefirst opening or port 44. In operation, a vacuum is created such thateach section of the Λ-notched friction material 10 adheres to a bottomsurface 46 of the link 42. An elastomer material 41, such as a rubber orurethane material is operatively attached, such as being glued, to anend 45 of each link 42, adjacent the first opening or port 44, forimproved vacuum sealing to the Λ-notched friction material 10. The link42 preferably further contains a second port 48 for reversing the vacuumand providing a positive force of pressure in order to deposit thefriction material 10 in a bonding nest 50, as can be seen in FIG. 6. Thelink loading device 40 holds the length of notched friction material 10firmly adjacent the bottom surface 46 of each link 42 during the formingoperation.

The bonding nest 50, as shown in FIGS. 6 and 12, defines acircumferentially extending annular recess 52 having a firstcircumferentially extending planar surface 54 for receiving the frictionmaterial 10. The surface 54 can generally extend toward a first interiorwall 55 in a planar direction or, alternatively, can have a recessedportion 56 adjacent the inner wall 55. The bonding nest 50 furtherdefines an interior wall 58. When the friction material 10 is placed inthe bonding nest 50, portions of the friction material 10 that areadjacent the Λ-notches contact the wall 58. Due to the geometry of theΛ-notches in the friction material 10, the friction material 10 has aspring-like action and is forced against the wall 58 of the bonding nest50. A detailed discussion of the Λ-notches in the friction material isprovided below.

Referring now to FIGS. 7-11, the operation of the multiple links loadingdevice 40 is schematically shown. The linking device 40 retrieves alength of friction material 10 from the support plate 27 or othersuitable position. It is to be understood that the support plate 27shown in FIGS. 7-11 can be the extension of the support plate 27 shownin FIG. 3. Alternatively, it is to be understood that the die stamp 8and multiple link loading device 40 can be separate operations. Ineither event, a similar type of support plate can be used to hold orsupport the length of notched friction material 10.

The links 42 of the multiple link loading device 40 are interconnectedsuch that each link 42 moves to a desired position with respect to theadjacent links. Each link 42 has a desired shape or configuration suchthat the plurality of links 42 can be pivoted into a desired position.As seen in FIGS. 7-10, each link 42 has an angled face 43 that allowsthe links 43 to be formed into a circular shape. The multiple linkloading device 40 includes an apparatus 46 operatively connected to thelinks 42 for moving or encircling the links 42 into the circular shape.The multiple link loading device 40 further includes an arbor 60 aroundwhich the links 42 are formed into the circular shape.

In operation, the encircling apparatus 46 causes the multiple linkloading device 40 to be wrapped around the arbor 60, generally shown inphantom in FIGS. 7-10. Each link 42 has the desired configuration suchthat the links 42 can be wrapped around the arbor 60 as shown in FIGS. 8and 9 to form a circular shape. Once the circular shape of the multiplelink loading device 40 is completed, as shown in FIG. 9, the arbor 60 ismoved in a radial direction such that the multiple link loading device40 is coaxially positioned around an axis A extending through thebonding nest 50 and the multiple link loading device 40.

It is to be understood that the arbor 60 is operatively connected to asuitable first translation device 64. The first translation device 64 isoperatively connected to the encircling apparatus 46 and the multiplelink loading device 40. The first translation device 64 provides radialmovement of the arbor 60 and the multiple link loading device 40 intothe coaxial alignment with the bonding nest 50. A second translationdevice 65 is also operatively connected to the encircling apparatus 46and the multiple link loading device 40. The second translation device65 provides axial movement of the arbor 60 and the multiple link loadingdevice 40 into position adjacent the bonding nest 50. The secondtranslation device 65 lowers the multiple link loading device 40 withthe circumferentially wound friction, into the bonding nest 50.

Referring now to FIG. 6 and then FIG. 11, the multiple link loadingdevice 40 provides a reversal of the vacuum being applied to thefriction material 10 through the port 44 by applying a reverse orpositive pressure air through the port 48. The positive pressure airforces the friction material 10 onto the surface 54 of the bonding nest50. Due to the Λ-notching of the friction material 10, the frictionmaterial 10 circumferentially rests adjacent the edge or wall 58 of thebonding nest 50.

FIG. 12 shows the greatly enlarged schematic cross-sectional view of thebonding nest 50 having a core plate 66 with adjacent friction materials10 and 10′. In certain embodiments, an outer edge 63 of the core plate66 is adjacent the wall 58 with dead end groove version. While not shownin FIG. 12, it should be understood that there is a space for frictionmaterial overhand on the open (restricted) exit embodiments. An inneredge 63′ of the core plate 66 is adjacent the interior wall 58′. Thecore plate 66 generally has layers of suitable adhesive material 68 and68′ on a first surface or face 67 and a second surface 69, respectively.The suitable layer of adhesive material 68 is adhered and dried to thesurfaces 67 and 69 of the core plate 66 earlier in the manufacturingprocess, as was described above with reference to FIG. 1. FIG. 12 showsan opposing length of notched friction material 10′ which is alsopositioned by a multiple linked loading device 40 onto the secondsurface 69 of the core plate 66. The bonding nest 50, as generally shownin FIG. 12, holds the friction materials 10 and 10′ and the core plate66 during a bonding process of the friction materials 10 and 10′ to thecore plate 66 to form a friction clutch plate.

FIGS. 13 and 14 show a schematic illustration of one bonding processwhere a plurality of bonding nests 50 are stacked together andpositioned in a clamping assembly 70 for heating in an oven (not shown).As seen in FIGS. 12-14, the bonding nest 50 can have a notched loweredge 55 which allows each adjacent bonding nest 50 to be stacked in asecure manner. The multiple nests 50 are stacked one on top each otherfor efficient production. As seen in FIG. 14, a bottom surface 59 of onebonding nest 50′ is positioned on a friction material in an adjacentbonding nest 50. Bonding pressure is maintained on each assembly of nest50, core plate 66 and friction materials 10 and 10′ by applying a forceand clamping the stack of multiple nests 50 with a post 74 havingopposing end plates 71 and 72, and a wedge 73.

FIG. 15 shows an induction bonding die 80 for applying heat and pressureto a core plate 66 and opposing strips of notched friction materials 10and 10′, In the embodiment shown in FIG. 15, the induction bonding die80 generally comprises an upper ceramic pressure plate 82 havingextending therethrough at least one induction coil 84. A phenolicinsulator plate 86 separates the induction coil 84 and the upper ceramicpressure plate 82 from an upper die plate 87 of the induction bondingdie 80. The induction bonding apparatus 80 further comprises a lower dieplate 94 and a phenolic insulator plate 96 which is operatively mountedthereto. A lower ceramic bond die 98 is positioned adjacent the phenolicinsulator plate 96. The lower ceramic bond die 98 defines a recess 100for receiving the length of notched friction material 10, the core plate66, and the opposing length of friction material 10′ (not shown). Theinduction bonding die 80 is placed into a conventional hydraulic press(not shown) and when energized, the upper ceramic pressure plate 82 isbrought into mating contact with the lower ceramic bond die 98 toprovide heat and pressure to the friction materials 10 and 10′ and coreplate 66. After the friction materials 10 and 10′ are bonded to the coreplate 66, a ceramic ejector plate 104 operatively ejects or removes thebonded clutch plate. The ejector plate 104 is operatively connected to asuitable means such as a pneumatic moveable means 106 which moves theejector plate 104 in a direction toward the upper ceramic pressure plate82 after the upper ceramic pressure plate 82 has been moved to an openposition. It is to be understood that various other apparatuses areuseful to place, and then remove, the friction materials 10 and 10′ andcore plate 66 from the induction coil apparatus 80.

FIG. 16 shows a conduction heating apparatus 110 comprising a firstheated platen 112 and an opposing or second heated platen 114.

The bonded nest assembly 50 (containing opposing friction materials 10and 10′ and a core plate 66 disposed therebetween) is positioned on theheating platen 114. An upper pressure plate 116 is mounted adjacent theupper heated platen 112. The upper and lower heated platens 112 and 114are brought into mating contact and heat and pressure are applied tocause the length of notched friction materials 10 and 10′ to bond to thecore plate 66.

Referring now to FIG. 17, a circumferentially wound friction material 10of the present invention is shown. The friction material 10 is producedfrom a continuous strip of a suitable friction material such as acomposite or fibered material impregnated with a resin as describedabove. The friction material 10 has a shape which is die cut so as touse nearly all of the available friction material during the blanking orcutting process.

The friction material 10 has an outer edge 214, an inner edge 216, and aplurality of connected sections 218 which are defined by a desirednumber of notches 220. The friction material 10 thus comprises aplurality of attached sections 218 separated by individual notches 220.

Each notch 220 radiates from the inner edge 216 in a direction towardthe outer edge 214.

FIGS. 18 and 19 show one preferred embodiment where each notch 220 has agenerally Λ-shape such that a first side 222 and a second side 223 ofthe notch 220 each has substantially the same length; that is, the sides222 and 223 of each notch 220 extend at the same, yet opposing, angle φ°from the center line X.

The desired number of notches 220 in a friction material 10 isdetermined by the end use application. The angle α° is determined bydividing the 360° by the number of notches desired. For example, 360°÷16notches=22.5°.

The sides 222 and 223 of the notch 220 define a groove, or gap, 224. Thewidth (W) of the groove 224, when the friction material 10 is in acircular shape (as shown in FIG. 19), is determined by an offsetdistance (D). The distance (D) is measured from a side (S) of the angleφ° which extends from an apex point (P) to the side 222 or 223 of thenotch 220. Thus, the width (W) equals the sum of the distances (D) and(D′), as shown in FIG. 19.

The notch 220 terminates at an apex 230. In a preferred aspect, the apex230 has a substantially circular shape. In other embodiments, however,it should be understood that other shapes such as oval, elliptical andthe like are also useful and, as such, are within the contemplated scopeof the present invention.

The apex 230 has a distal end 234 which terminates at a preferreddistance (H) from the outer edge 214. The distance (H) defines a bridgesection 232 of the friction material 10. The bridge section 232 extendsbetween the distal end 234 of the apex 230 and the outer edge 214.

Referring now to FIG. 18, the bridge 232, which has the distance (H) asdefined by the outer edge 214 and the distal end 234 of the apex 230, isschematically shown. The shape of the apex 230 prevents the bridgesection 232 from fracturing or separation; that is, when the frictionmaterial is in a circular shape a portion (C) of the bridge section 232is compressed, while a portion (T) of the bridge section 232 isstretched, or under tension. The compressed portion (C) extends from theapex point (P) to the distal end 234 of the apex 230. The tensionedportion (T) extends from the apex point (P) to the outer edge 214 of thefriction material 10.

In a preferred embodiment, the apex 230 has a diameter that ranges fromabout 0.75 mm to about 1.25 mm. The height, or distance, (H) ispreferably about 0.75 mm to about 1.5 mm. The compressed portion (C) isbetween about 20 to about 40% of the distance (H), while the tensionedportion (T) is between about 60 to about 80% of the distance (H). Forexample, in certain embodiments where (H) ranges from about 0.75 toabout 1.5 mm, the compressed portion (C) has a length that rangesbetween about 0.15 mm to, about 0.60 mm, while the tensioned portion (T)has a length that ranges between about 0.45 mm to about 1.2 mm.

The bridge section 232 preferably has the above described desiredgeometry since, if the bridge section 232 is too large, the frictionmaterial tears inconsistently, and, if the bridge section 232 is toosmall, the friction material is too weak. The shape of the apex 230allows for controlled and consistent forming of the friction material10. The bridge section 232 provides a spring action to the Λ-notchedfriction material 10 when the Λ-notched friction material 10 is formedinto a circular shape and placed into a friction plate bonding nest.

The Λ-notched friction material tends to maintain its straight shapesuch that, when the Λ-notched friction material is circumferentiallypositioned in the bonding nest 50, as shown in FIG. 12, there is anoutward force or spring-type action applied against the side wall 58 ofthe bonding nest 50. The outer edge 214 of the Λ-notched frictionmaterial 10 is pressed against the interior side wall 58 of the bondingnest 50 to hold the friction material 10 in place without sliding ormoving. Also, the spring-type force maintains the desired spacingbetween the sections 218 of the friction material such that the width ofeach groove 224 in the friction material 10 is consistent.

The Λ-notched friction material 10 is a unitary piece, as compared tothe multiple friction segments. The unitary Λ-notched friction material10 does not require delicate handling and does not require the handlingof many prior art type individual segments that had to be individuallyand carefully positioned on the core plate.

The spring action of the Λ-notched friction material 10 allows thefriction material 10 to be placed in the bonding nest without concernthat the friction material 10 will fall out of the bonding nest.Further, no preadhesion of the friction material 10 to the core 66 isnecessary during handling and assembly of the core plate, prior to thebonding step.

The sides 222 and 223 of the notch 220 are configured to create adesired fluid flow pattern in the groove 224 when the friction material10 is circumferentially adhered to the clutch plate 66. The radiallyextending groove 224 creates a desired hydrostatic pressure as fluidflows into the groove 224 and terminates in the apex 230. This pressurehead in the groove 224 and apex 230 is intended to assist in separatingthe clutch plates 66. Upon release of the clutch, the pressure also actsto eliminate parasitic drag when the plates are released and separated.The sides 222 and 223 of the groove 224 can be oriented so that, forinstance, the groove 224 has substantially parallel sides, as shown inFIG. 17, when formed into a circular shape.

Referring now to FIG. 20, an alternative embodiment of a frictionmaterial 310 is shown where the friction material 310 has an outer edge314, an inner edge 316 and a plurality of connected sections 318. Thefriction material 310 includes a plurality of off-centered Λ-shapednotches 320 which define the connected sections 318. Each notch 320radiates from the inner edge 316 to the outer edge 314. A first side 322of the notch 320 has a shorter length than a second side 323 of thenotch 320. Each notch 320 terminates at an apex 330, as described abovewith respect to the apex 30 in FIG. 17.

Referring now to FIG. 21, another embodiment of the invention is shownwhere a friction material 410 has an outer edge 414, inner edge 416 anda plurality of connected sections 418. The friction material 410 isprovided with a desired number of notches 420 which define the connectedsections 418. Each notch 420 radiates from the inner edge 416 in adirection toward the outer edge 414. In the embodiment shown in FIG. 6,the notch 420 has an off-centered Λ-shape such that a first side 422 ofthe notch 420 extends in an offset rearward direction from the inneredge 416 toward the outer edge 414. A second side 423 extends in agenerally straight radial direction toward the outer edge 414 when thefriction material 410 is circumferentially placed on a clutch plate (notshown). Each notch 420 terminates at an apex 430, in a manner asgenerally described above.

In each of these embodiments, the pressure created in the groove 224between the sides 222 and 223 of the notch 220 provides an appropriatepumping action to press fluid into the groove 224, thereby creating, apressure head in the groove 224 and in the apex 230. The amount ofangled orientation between the sides 220 and 223 of the notch 220 isdetermined by the amount of cooling fluid flow desired and the amount ofpressure build-up desired. The friction material 10 of the presentinvention is easily adaptable to pumping oil radially outward atdifferent rates depending on the orientation of the notches. Thefriction material produces a large pressure build up due to the apex onthe Λ-shaped notch. The friction material is universally applicable toany desired objective, depending on its relative orientation and thedirection of rotation of the plate.

In contrast to the embodiment shown in FIG. 11, where the outer edge 214of the bridge section 232 is adjacent and coterminous with the edge 63of the core plate 66, FIG. 22 shows another embodiment where the coreplate 66 has the friction material 10 bonded thereto beyond the edge 63of the core plate 66. In certain bonding processes, the frictionmaterial 10 is positioned on the core plate 66 such that an overhangportion 233 of the bridge section 232, which is adjacent the apex 230,extends beyond the outer edge 63 of the core plate 66.

It is to be noted that, in the embodiment shown in FIG. 11, the bridge232 of the friction material 10 is coterminous with the edge 63 of thecore plate 66. The notch 220 defines the groove 224 which is a fulldepth, dead end or closed groove 224. The closed end groove 224eliminates passage of fluid through the groove 234, which is especiallyuseful in low lubrication applications.

In other applications it is desired to have a predetermined amount offluid flow through the grooves 224. FIG. 23 shows the friction material10 bonded to the core plate 66 where at least a portion of the overhangportion 233 of the outer edge 214 of the friction material 10 isremoved. In certain preferred embodiments, a predetermined amount of theouter edge 214 (i.e., the overhang portion 233) is removed by beingchamfer sanded. The notch 220 thus defines a groove 224′ that ispartially restricted. The restricted opening groove 224′ allows alimited, or restricted passage of fluid through the groove 224′,

FIG. 24 shows a cross-sectional view through a chamfer sanded notch220′, FIG. 25 shows a cross-sectional view through the “chamfer-sanded”removed friction material 10 from the one of the connected sections 218of the friction material 10. The removed friction materials 10 and 10′now define angled faces 215 and 215′, respectively. The desired amountof friction material remaining bridge section R is shown as the distancebetween the arrows in FIG. 24. The amount of chamfer-sanded removedmaterial is removed by sanding the friction material 10 at an angle β°.The angle β° is measured from a line perpendicular to a plane defined bythe annular surface 67 of the core plate 66. In certain embodiments, theangle β° at which the friction material is removed is between about 25to about 35°, and most preferably about 30°.

In still other applications, it may be desired to fully open the grooves224. In such applications, the amount of remaining bridge material R iszero; that is the entire thickness of the friction material 10 isremoved.

Table 1 below shows the friction material utilization for variousconventional art friction facing materials as compared to the edge woundnotched material of the present invention. As can readily be seen, thepresent invention provides for more efficient utilization of thefriction material than the conventional materials.

TABLE 1 Material Utilization Comparison Friction Plate with OD = 146 mm,ID = 121 mm Conventional 2-out Full ring Blanking = 25% Conventional3-Segment Facing = 54% Conventional 20 Segment Multisegment = 78% EdgeWound Notched Material of Invention = 88%

It is to be noted that conventional, full ring blanking of frictionmaterial typically yields 25% material utilization (25% of themanufactured friction material ends upon the clutch plate and 75% endsup in landfills). In comparison, with the edge wound notched strip offriction material of the present invention, the material utilization isgenerally determined as follows: Final Friction Area/MaterialConsumed=πRO²-πRi²/(Strip Length×Strip Width)=5,362 mm²/6,129 mm²=88%.

EXAMPLE I

For calculations for a Λ-notched friction material:

O.D.=146.15 mm (5.7539″)

I.D.=120.55 mm (4.7461″)

True circumference of round facing=πO.D.=5.7539π=18.077″ The edge-woundfriction material does not have a radiused O.D. but instead, a series ofstraight lengths of friction material. For a 16 notch design, as seen inFIG. 17, 360°/16=22.5°.

H=radius of part=5.7539/2=2.877″

Without stretch or tear at corner of Λ-notch, pitch would be =2×0

(opposite)

0/2.877=SIN 11.25°

0=2.877 SIN 11.25°

0=2.877 (0.1951)

0=0.5613″

2(0)=1.1225″

True perimeter with 16 straight lengths and without stretch or tear=16×1.1225=17.9608″.

For this example, it is estimated that 70% of the material will stretchor tear and 30% will compress.

70%×0.060″=0.042″

Estimated Ro_(p1)=2.877-0.042″=2.835″

O.D_(p1)=2πRo_(p1)=17.813

Notch Pitch=17.813÷16=1.1133

EXAMPLE II

A direct/intermediate clutch plate was chosen as the part to tool andevaluate. All samples were produced with production glued core plates,production friction materials (4 grades), and production bonding nest(except induction bond samples).

The progressive blanking die 8 was used to blank the notches and theinside edge of the friction material. The outer edge remains straightand becomes the outside diameter of the friction material. The notchgeometry, at least in part, determines the resulting oil groove widthand how well the strip of friction material conforms to the bondingnest. The bonding nest 50 is used to concentrically align the frictionmaterial 10 with the preglued core plate 66. The pitch, or number, ofΛ-notches in friction material also has an influence on how well thecircular formed friction material conforms to the bonding nest. TheΛ-notched friction material was formed into a 360° ring, and insertedinto a bonding nest.

In various experiments, the depth, or length, of the notch was varied,producing bridge section widths varied from 0.50 to 1.80 mm. In oneembodiment, the blanked Λ-notched friction materials were most stable(not easily broken down) when the bridge section had a width of about0.70 to about 1.50, and most preferably at least about 0.75 to about 1.0mm. One particularly useful friction material has a bridge section widthof about 1.14 mm and a radius of the apex of the notch of about 1.02 mm.

The Λ-notched edge wound friction plate is manufactured consistentlyusing the blanking, assembly and bonding methods as generally describedherein. The manufacturing process can be performed separately in batchesor can be integrated into a fully automated process. An automatedprocess results in further significant cost reductions due to theefficient use of friction material, and also due to the low cost of themachine assembly as compared to a labor intensive manual process. Theprocess is also more reliable than the conventional multi-segmentprocesses because there is no need to apply additional adhesives to theplate and/or friction material.

According to the present invention only three components are beingassembled together: the first friction material, the core plate and thesecond, opposing friction material. In contrast, for example, in certainprior art processes such as the multisegment processes, 41 separatecomponents are used; one core plate and 20 segments on each side of thecore plate.

Further, according to the present invention, the core plate does nothave to be turned or flipped over in the assembly process, unlike withthe multisegment plate process. Rather, the friction material/core plateassembly is bonded in the same nest as it was assembled.

Yet another advantage of the present invention is that the Λ-notchedgrooves created by the notches blanked into the strip of frictionmaterial eliminate the need for separate (and expensive) mill groovingor molding operations.

Still another advantage is that the Λ-notched grooves provide importantperformance advantages over the conventionally designed clutch plates,specifically in reduced drag, reduced hot spotting, and increasedfriction coefficient. These performance improvements are especiallyenhanced in low lubrication flow applications.

EXAMPLE III

The results of MuPVT, Drag, T-N, and Hot Spot design verification testsperformed on friction plates utilizing the unitary, circumferentiallyedge wound Λ-notched friction materials (both with dead end, closedgrooves and with partially opened grooves) are shown below.

FIGS. 26-31 show standard SAE (981D) MuPVT test results for frictionmaterials with exits, FIGS. 27, 29 and 31, (or restricted openings) andwithout exits, FIGS. 26, 28 and 30, (dead end, closed grooves). Thematerials tested were BW 4501 using a standard fluid, standard reactionplate with temperatures at 50° C. (for FIGS. 26A, 26B, 27A, 27B, 28A,28B, 29A, 29B, 30A, 30B, 31A and 31B) and at 110° C. (for FIGS. 26C,26D, 27C, 27D, 28C, 28D, 29C, 29D, 30C, 30D, 31C, and 31D). Due to asuppressed initial torque, the core plates with grooves that dead-end atthe OD produced extended stop times at low temperature (50C) and facingpressure (295 kPa). This same effect is present at 591 kPa, but to alesser degree. Under the other conditions of the test (Procedure 981D),the Λ-notched friction material clutch plates perform similarly toconventional cut parallel grooved plates. When the Λ-notched grooves aremodified so as to create exits at the OD, the performance issatisfactorily comparable to conventional cut parallel grooved plates,under all test conditions. Also, the initial and midpoint coefficientsare higher with the restricted exit notched friction material design.

FIG. 32 shows the drag test results: comparing the open pack dragcharacteristics of the unitary, notched friction material (with exits),to that of plates with no grooves, plates with 56 molded radial grooves,and plates with 25 cut parallel grooves. The unitary notched frictionmaterial plates have drag torques which are 10% lower than 56 moldedgrooves, 28% lower than standard cut groove and 35% lower than ungroovedplates.

FIG. 33 shows the standard SAE (1015A) T-N test results. No differencein durability between the unitary, notched friction materials (withexits and without exits) was noticed and the notched friction materialsare comparable in durability to plates with 25 cut parallel grooves.

FIG. 34 shows the standard 1014A Hot Spot test results. The unitary,notched friction materials (without exits) have better hot spotresistance than the notched friction materials (with exits). Theperformance of the unitary, notched friction material (with exits) iscomparable to plates with 25 cut parallel grooves.

Overall, clutch plates made with the notched friction material (noexits) and the OD chamfer sanded friction materials (with exits)performed as well or better as the clutch plates with 23 cut parallelgrooves.

The method of manufacture described herein has no undesirableproperties/characteristics of the finished clutch plate. The standardtests described above were conducted to assess the key characteristicsof friction plates, i.e., torque capacity, shift quality, durability,hot spot resistance, and open-clutch spin loss. The test samples wereprepared utilizing production intent processes. The baseline plates werestandard plates which have 23 cut parallel grooves. Both the testsamples and the baseline plates were lined with a production madefriction material.

All testing was conducted in Exxon B fluid. A standard SAE frictionmachine was used in the running of MuPVT Procedure 981, T-N DurabilityProcedure 1015, and Hot Spot Procedure 1014. The drag testing wasperformed on a OWC freewheel machine outfitted with genuine transmissionhardware.

Referring now to FIG. 35, a schematic view of an apparatus for making acore plate having a Λ-notch friction material thereon is generallyprovided. The apparatus 500 generally includes an indexing table 502having a circular or annular top 504 rotatably mounted in a suitablemanner, with, for example, a motor (not shown) for rotating the top 504at a predetermined rate of speed.

A plurality of core platen or bonding nest platforms 508 are rotatablymounted on spindles (not shown) that are positioned on the top 504 ofthe indexing table 502. Each of the nests 508 is in communication with,for example, a motor (not shown) for rotating the platform 508 as in thedirection of arrow 509. In the present embodiment, there are eightplatforms 508. However, the number of platforms 508 can vary, dependingon the application.

The apparatus 500 includes a plurality of work stations. At Station #1,a bonding nest 510 is inspected for verification of vacancy (i.e., thebonded clutch plate was evacuated in Station #8). At Station #2, a firstdispensing apparatus 520 for positioning a first length 524 of notchedfriction material is positioned adjacent the indexing table 502. Thefirst dispensing apparatus 520 dispenses the first desired length 524 ofnotched friction material into the bonding nest 510. The nest 510rotates in the direction of arrow 509 as the friction material 524 isdeposited in the bonding nest 510.

The bonding nest 510 with the first length of friction material 524 isadvanced to Station #3 where a first suitable inspection device 530,such as a camera, is used to inspect placement of the friction material524 in the bonding nest 510.

At Station #4, a glued core 534 is loaded by a loading apparatus 536onto the first length of notched friction material 524 in the bondingnest 510.

At Station #5, a second dispensing apparatus 540 for positioning asecond length 544 of notched friction material is positioned adjacentthe indexing table 502. The second dispensing apparatus 554 dispensesthe second length 544 of the notched material on an opposing side of thecore 534.

The nest 508 is further advanced to Station #6 where a second suitableinspection means, such as a camera 550, is used to inspect placement ofthe second length of friction material 544 on the core 534.

Thereafter, the core 534, having the first and second lengths offriction material 524 and 544, respectively, adjacent the core 534, isadvanced to a Station #7 for bonding using, for example, a hydraulicC-frame press 560 with an induction heated die to set the glue and bondthe notched friction materials 526 and 546 to the core plate 534.

Thereafter, the bonded friction plate is advanced to Station #8 where aconveyor device 570 removes the bonded plate 534 onto a conveyor means574.

Referring now to FIG. 36, a schematic view of another type of apparatusfor making a friction plate having a Λ-notch friction material thereonis generally provided. The apparatus 600 generally includes an indexingtable 602 having a circular top 604 and is rotary indexed by a motor andgearbox (not shown).

A plurality of bonding nests 608 are mounted on the top 604 of theindexing table 602. In the present embodiment, there are eight bondingnests 608, however, the number of nests 608 can vary, depending on theapplication.

The apparatus 600 includes a plurality of work stations. At Station #1,a coil of friction material 610 is fed by a powered stock straightener612 to a stamping press 614 which contains a stock feeder 616 and aprogressive stamping die 618. The stamping die 618 stamps out theΛ-notch and inside radius geometry, as shown in FIG. 18. The stampingdie 618 contains a cam actuated punch that is activated after apredetermined number of press strokes, thereby cutting off the notchsection to a predetermined length. The length of Λ-notched material istransferred to a pickup location either by a servo motor driven wheel orby a linear translation device 619 to the multiple link loading device620. The multiple link loading device 620, as described in detail above,has vacuum ports in each link which holds the Λ-notched frictionmaterial while forming the Λ-notched friction material into a circularshape. The multiple link loading device 620 and formed friction materialare moved over the bonding nest 608. The second translation device (notshown) lowers the multiple link loading device 620 and formed frictionmaterial into the cavity of the bonding nest 608. The vacuum is reversedand the multiple link loading device 620 is raised, leaving the formedfriction material inserted in the bonding nest 608.

The bonding nest 608 with the first inserted friction material isadvanced to Station #2 where a first suitable inspection device 522,such as a camera, is used to inspect for proper placement of thecircular formed friction material 619 into the bonding nest 608.

At Station #3, a glued core plate 624 is loaded by a loading apparatus626 onto the first formed and inserted friction material in the bondingnest 608.

At Station #4, a second set of blanking and loading apparatus 620′similar to that in Station #1 produces, forms and inserts a secondΛ-notched friction material on an opposing side of the glued core plate624.

The nest 608 is further advanced to Station #5 where a second suitableinspection means 690, such as a camera, is used to inspect for properplacement of the second Λ-notched friction material on the core 624.

Thereafter, the core 624, having the first material and second 629material of Λ-notched friction material adjacent the core 624, isadvanced to Station #6 for bonding using, for example, a hydraulicC-frame press 660 with an induction heated die to polymerize the glueand bond the Λ-notched friction materials to the core 624.

Thereafter, the bonded friction plate is advanced to Station #7 where apick and place device 670 removes the bonded plate and places it onto anexit conveyor 680.

At Station #8, the bonding nest 608 is inspected for verification ofvacancy of any components.

It should be understood that the above-described apparatus is an exampleof one particular type of apparatus that can be utilized to with thepresent invention. Other types of apparatus can be used such as aninline array apparatus, and the multiple linked loading device describedabove.

The above descriptions of the preferred and alternative embodiments ofthe present invention are intended to be illustrative and are notintended to be limiting upon the scope and content of the followingclaims.

I claim:
 1. An apparatus for making a notched friction materialcomprising: a stamping die for producing at least one firstpredetermined length of friction material; a multiple link loadingdevice comprising a plurality of links, each link having at least onevacuum port through which a vacuum is formed when the multiple linkedloading device is adjacent the first predetermined length of thefriction material; an encircling apparatus operatively connected to themultiple link loading device for moving the links into a circular shape;and at least one translation device operatively connected to themultiple link loading device for moving the encircling apparatus in adirection toward a bonding nest and for placing the length of frictionmaterial adjacent the bonding nest; the bonding nest being positionedfor receiving the first length of friction material, the vacuum ports inthe multiple link loading device being capable of reversing the vacuumpressure such that the first length of friction material is deposited ina circular shape in the bonding nest.
 2. The apparatus of claim 1,further including: a core plate loading device for placing an annularcore plate on the first length of friction material within the bondingnest; and the multiple linked loading device also being capable ofsupplying a second predetermined length of friction material onto a topannular surface of the core plate.
 3. The apparatus of claim 2, furtherincluding a chamfering device for removing a predetermined amount of anouter edge of the friction material adjacent an outer edge of the coreplate.
 4. The apparatus of claim 2, further including a heating devicefor heating at least one bonding nest to cause the first and secondlengths of friction materials to adhere to the core plate.
 5. Theapparatus of claim 4, wherein the heating device comprises an oven forheating a plurality of bonding nests stacked together.
 6. The apparatusof claim 2, further including a heating device which comprises aninduction coil apparatus for applying heat to the core plate and thefirst and second lengths of friction material.
 7. The apparatus of claim3, further comprising a heat conduction apparatus comprising a firstheated platen and an opposing heated platen and a means for placing thecore plate and opposing lengths of friction materials therebetween forapplying heat to cause the first and second lengths of friction materialto bond to the core plate.
 8. The apparatus of claim 1, wherein thefriction material comprises a plurality of connected sections and aplurality of notches, each connected section being defined by adjacentnotches in the friction material, and each notch having an apex whichcompensates for tear and compression of the friction material when thefriction material is formed into a circular shape.
 9. The apparatus ofclaim 8, wherein each notch has an angle generally defined by a formulacomprising: 360°/number of notches in the friction material.
 10. Theapparatus of claim 8, each notch has a substantially Λ-shape.
 11. Theapparatus of claim 8, wherein the apex of each notch has a substantiallycircular shape.
 12. The apparatus of claim 8, wherein the frictionmaterial has about 12 to about 40 notches.
 13. The apparatus of claim 8,wherein at least one of the notches defines opposing, radially extendingand parallel sides when the friction material is formed into a circularshape.
 14. The apparatus of claim 8, wherein at least one of the notchesdefines a first radially extending side which extends at a first anglefrom an inner edge of the friction material and further defines asecond, opposing radially extending side which extends at a second anglefrom the inner edge of the friction material.
 15. The apparatus of claim8, wherein at least one notch defines a groove, which groove is formedwhen the friction material is formed into the circular shape, the groovehaving a width W that is determined by an offset distance D fromopposing sides of the notch.
 16. The apparatus of claim 15, wherein thedistance D is measured from a side of an angle to the side of the notch,the angle extending from an apex point P adjacent the apex to an inneredge of the friction material.
 17. The apparatus of claim 8, when theapex terminates at a distance H from an outer edge of the frictionmaterial, the distance H defining a bridge section of the frictionmaterial which extends between a distal end of the apex and the outeredge of the friction material.
 18. The apparatus of claim 17, wherein aportion C of the bridge section is compressed, while a portion T of thebridge section is stretched or under tension, the compressed portion Cextending from an apex point P to the distal end of the apex and thetensioned portion T extending from the apex point P to the outer edge ofthe friction material.
 19. The apparatus of claim 18, wherein thecompressed portion C comprises between about 20 to about 40% of thedistance H, while the tensioned portion T comprises about 60 to about80% of the distance H.
 20. The apparatus of claim 8, wherein each notchdefines a closed end groove on the friction material.
 21. The apparatusof claim 8, wherein a predetermined amount of an outer edge of thefriction material is removed by a chamfering device whereby at least onenotch defines at least a partially opened groove on the friction plate.22. The apparatus of claim 21, wherein the friction material ispositioned adjacent a core plate such that an overhang portion of thefriction material extends beyond the outer edge of the core plate, andwherein the overhang portion is removed from the friction material. 23.The apparatus of claim 22, wherein the predetermined amount of the outeredge of the friction material is removed at an angle β° of between about25 to about 35° from a line perpendicular to a plane defined by anannular surface of the core plate.